Circular heading machine

ABSTRACT

A circular heading machine for excavating tunnels by advancing a machine in stepwise fashion and erecting tunnel supports, having an elongate machine body at the forward end on which a forwardly directed cutter boom is mounted. Rams advance the machine body in stepwise fashion acting against grippers and a profile ring limits peripheral movement of the cutter boom to form an accurate profile. A gathering apron is provided at the forward extremity of the machine body. The cutter boom is mounted on a sliding carriage longitudinally movable on and independently of the machine body and a hood overlies the apron. A cage structure extends rearwardly from the hood structure and surrounds the body cutter and sliding carriage and tunnel support erecting members are provided externally of the cage structure, directly behind the hood structure. The hood is a semi-circular member supported by hydraulic rams for height adjustment.

This invention relates to circular heading machines for excavatingtunnels.

It is well known to cut tunnels by advancing a machine in step-wisefashion and to erect tunnel supports behind the machine. However, asthese supports are behind the machine, the machine itself is protectedby some other means such as shields, but shields can become trapped byconvergence, especially in deep mining and consequently tunnelling canbe delayed while the shield is freed.

An object of this invention is to obviate or mitigate the aforementioneddisadvantage.

According to the present invention there is provided a circular headingmachine comprising an elongate machine body having at its forward end aforwardly directed cutter boom mounted thereon, means to advance themachine body in step-wise fashion, means to limit peripheral movement ofthe cutter boom to form an accurate profile and a gathering apron at theforward extremity of the machine body, characterised in that the cutterboom is mounted on a sliding carriage longitudinally moveable on andindependently of the machine body, a hood overlies the apron, a cagestructure extends rearwardly from the hood structure and surrounds theboom cutter and sliding carriage and means are provided externally ofthe cage structure, directly behind the hood structure for erectingcircular tunnel support structures over the machine body, erection ofthe tunnel support structures taking place simultaneously with operationof the cutter.

Preferably, the hood is a semi-circular member supported by hydraulicrams for height adjustment.

An embodiment of the present invention will now be described, by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a side elevation of a circular heading machine according tothe invention;

FIG. 2 is a plan view of FIG. 1;

Figs. 3 to 5 are side elevations of the machine illustrating, with FIG.1, the cycle of operation;

FIG. 6 is a rear elevation of the lines VI--VI of FIG. 1 showing tunnelsupport erection apparatus.

FIG. 6A is a rear elevation of the lines VIA--VIA of FIG. 1 showing therear support leg;

FIG. 7 is a detail illustrating lagging between the tunnel supports; and

FIG. 8 a detail illustrating a trailing arm.

The circular heading machine has an elongate body 10 which mounts acutter boom 11 at its forward end, the boom 11 being carried on asliding carriage 12 which is slidably moveable on the machine body 10 bythrust jacks 13. The cutter boom 11 carries a conical cutter head 14, bywhich a tunnel 15 can be excavated; movement of the boom is manuallycontrolled via tilting jacks 11A and slewing jacks 11B, by an operatorseated in the sliding carriage.

At the forward extremity of the machine body there is a gathering apron16 of semi-circular form which carries windmill or gathering arms 16Aand above the apron there is a semi-circular hood 17; this hood forms astone/dust guard as illustrated in FIG. 1 for use as a temporary roofsupport if required and it may be provided with trailing fingers (FIG.8) as hereinafter described.

The hood is supported by hydraulic rams 17A which serve to lower thehood if necessary for the insertion of lagging strips 45 (FIG. 6)hereinafter described and to permit controlled lowering of the hood inthe event of severe convergence or collapse of the roof.

The apron and hood converge rearwards and terminate in a profileguidance ring 18 and on the cutter boom there is a profile collar 18'which can run round the inner face of the ring 18 thus limiting themovement of the boom.

Immediately behind the apron/hood structure is a tunnel-supportmechanical erection apparatus 20 by which ring girders can be erectedover the machine body as hereinafter described with reference to FIG. 6.

A cage-structure 21 is provided on the machine body below the level ofthe top of the hood 17 to enclose the boom 11 and carriage 12 and thesupport erection apparatus 20 is external of the cage 21. Tunnel supporterectors can therefore work in safety on a platform 22 on the machinebody even while the cutter 14 is in operation.

Towards the rear of the machine body 10, a radial gripper mechanism 23is provided having three segmental grippers 24 which are radiallyextendible to engage the sides and floor of the excavated tunnel. Thrustjacks 25 and 25A are connected between the lowermost gripper 24 and anunderframe 26 on the machine body 10 and between side grippers 24 andlongitudinal beams 26A also on the machine body. When the grippers 24are firm against the tunnel, the jacks 25 and 25A can extend to push themachine body forward; when the grippers are retracted the jacks 25 and25A can be retracted to draw the gripper mechanism 23 forward.

Rearward of the gripper mechanism a segmental support leg 27 is mountedon the machine body 10 and is extended downwards to engage the tunnelfloor when the gripper mechanism is to be retracted and when the sidegrippers are being adjusted to align the machine transversely, thus tohold the machine in its existing vertical alignment. The support leg 27is part of a centering structure 27A which is transversely slidablymounted in the machine body 10 and includes side jacks 27B. The jacks27B operate sequentially with support leg 27 to ensure that the latteris automatically centralised in the tunnel before engaging the tunnelfloor.

To achieve this the side jacks 27B which are hydraulic jacks areconnected through an equal split flow divider so that their flows areequal; thus if one jack engages the tunnel wall first, it will push theentire jack structure transversely relative to the machine body awayfrom that side until the other side jack engages its side of the tunnel,after which the support leg 27 will be in a centered position relativeto the tunnel. Once the support leg has been lowered, the rear end ofthe machine body can be transversely adjusted via the side grippers 24to give accurate directional positioning of the machine required, ashereinafter explained.

The machine body carries an integral scraper chain conveyor section 30which runs from the gathering apron, under the machine body thenupwardly towards the rear end, exiting in a rearward extension 31 beyondthe machine body for transfer of excavated minerals to a bridge conveyor32 trailed by the machine. The bridge conveyor is aligned below conveyorextension 31 and on the former is slidably mounted a deflector structure32A which when in one position is clear of material dropping on to thebridge conveyor 32 and when in the other position deflects the materialon to the floor at the side of the bridge conveyor to create an infill33 when required. The machine operates in cycles as illustrated in FIGS.1 and 3 to 5, and described hereinafter.

Tunnel support erection is carried out by erectors working on theplatform 22 situated immediately behind the apron/hood structure so thatthe supports are erected over the machine body and in advance of theboom operator. A secondary platform 22A is provided on each side forerectors to fit tie rods 52 hereinafter described.

Segments of ring girders 40 (FIGS. 1 and 6) are delivered, e.g. bymonorail (not shown) to the rear of the machine and delivered therefromvia a hydraulically driven chain hauled carrier 41 (FIG. 6) running viawheel 42 on a longitudinal structure 43 overlying the machine body tothe erection area behind the hood 17. Structure 43 is bodily adjustablelongitudinally and vertically relative to the machine body 10 byhydraulic rams 44 and 45 (FIG. 1) to manipulate the ring supports intoposition. At the erection area directly behind the apron/hood all butone of the segments 40 are mounted in turn on the mechanical erector 20which is a framework carrying a circular chain 46 (FIG. 6) driven bysprockets 47 then jointed and hauled round the tunnel perimeter until analmost complete but collapsed ring has been built. Over the top halfsection lagging in the form of wire mesh panels or corrugated sheets 48is introduced between the last panel of lagging and the new collapsedring girder by inserting them alternately into arcuate slot 49 and space50 and raising them to overlap the previous set.

Those sections of the ring girder now in position are expanded by themanoeuvring adjustment of structure 43 to trap the lagging 48 and tomeet the perimeter of the lower part of the tunnel; thus the finalsection of the ring girder is placed in position on carrier 41 and byadvancing the carrier is presented against the as yet unexpanded ringportions already in position. At this stage adjustable legs 51 of thecarrier 41 are manually brought out and locked against the ends of thepositioned sections 40 and the entire structure 43 is lifted byhydraulic rams 45 to expand the positioned sections radially to provideroom for the final section which is advanced into position either bymoving structure 43 bodily forward using hydraulic rams 44 or byadvancing carrier 41 or both.

A ring expansion joint (not shown) is then fitted and to give extratunnel support the machine is designed to allow this expansion joint tobe located in different positions on adjacent ring girders so that theweakest point in the girder is not always in the same relative position.

The tie rods 52 (FIG. 6A) are loosely bolted to the previous ring andthe entire new ring is drawn back on carrier 41 by the hydraulic rams 44to abut against the tie rods.

The new ring is then loosely bolted to the tie rods after which a finalexpansion of the new ring is carried out using known methods, e.g.mechanical screw jacks and final tightening of the bolts is made.

Cycle

The machine operates in cycles as illustrated in FIGS. 1 and 3 to 5 (inthe latter Figs. the jacks 25A are omitted for reasons of clarity).

Before beginning the cycle and with the entire machine advanced to theface:

1. The boom sliding carriage 12 is in its retracted position so that thecutter 14 is just clear of the mineral face.

2. The side jacks 27A are extended to automatically centre the lowersupport leg 27 in the tunnel and then lower it to the floor.

3. The gripper mechanism 23 is retracted (chain lines) and drawn forwardby retraction of the thrust jacks 25 and 25A.

4. The transverse alignment of the machine 10 is checked by knownmethods of alignment, e.g. laser beams 53 and target 54 on the machineand if necessary set to its correct position by pushing with the lefthand or right hand wall gripper 24A against the tunnel wall thus slidingthe machine across the centering structure 27A which is firmly locatedagainst the tunnel wall.

5. The wall grippers 24A are then retracted and the floor gripper 24 islowered followed by retraction of the lower support leg 27 and sidejacks 27A and the vertical alignment is checked by the same means as (4)above using the floor gripper.

6. With the floor gripper 24 still in position both side grippers 24Aare then set hard against the tunnel walls.

7. Lagging 48 (FIG. 6) is introduced into arcuate slot 49 and into thespace 50 between the hood 17 and the roof and a ring girder 40 isassembled and expanded finally thus trapping this lagging between girderand tunnel. The machine is now ready to cut into face 35.

8. The cutter boom carriage is advanced to sump-in the cutter head andexcavate to a depth of 0.5 meter (FIG. 1). The head can move universallywithin the limits set by the profile ring 18 and forms a circular holeslightly in excess of the required tunnel diameter with a new mineralface 35A.

9. Whilst this operation is in progress a set of ring segments arebrought forward from the rear, loaded into the erector 20 and carriedround into position.

10. After that excavation, the cutter boom carriage is retracted and themachine advanced 0.5 meter carrying the partially assembled ring in theerector with it to once again present the cutter head to the mineralface now 35A. During this time the lagging 45 covers the `exposed`ground by bridging between the initial set ring and the hood.

11. The carriage is then advanced again (FIG. 4) to sump in and excavateanother 0.5 meter to form a new mineral face 35B.

12. After that excavation the carriage is retracted and the machineadvanced a further 0.5 meter (FIG. 5) thus having achieved the first 1.0meter advance of the machine.

13. The cycle for 1.0 meter advance is now completed with the cutter 14just clear of the mineral face 35B. The gripper mechanism 23 isreleased, drawn forward and repositioned.

14. The cycle can now be repeated but steps 7 and 8 are combined so thatin the process of excavating the next 0.5 meter, lagging is positionedaround the hood again to overlap the existing lagging, the last ringsegment is loosely fitted, and the tie rods 52 are secured between thefirst and second rings as previously described. The entire ring ispositioned by manoeuvring structure 43 then expanded finally intoposition.

In an alternative hood construction, FIG. 8 rearwardly extending fingers55 are resiliently connected to the front edge of each hood plate 17 andextend back by such a length that they overlie not only the ring girderbeing erected but also the last fully erected ring girder. When themachine reaches the end of its cycle, the structure 43 is manoeuvred toposition the ring girder being erected and during the new cycle when themachine is pushed forward the trailing fingers are drawn clear of thepreviously last erected ring girder to overlie the new last erected ringgirder.

Dust extraction ducts 56 are fastened to the machine body whereby whenair is blown into the tunnel and over the machine, dust from theexcavation will be drawn into the top of hood 17 and through theventilation ducts 56 to exit from the rear into a dust collection unit(not shown) thus enabling the erectors to operate in a relatively dustfree atmosphere.

A hydraulic power pack 57 can be trailed behind the machine or, asillustrated in FIG. 1 located on the machine body and is used to powerall the machine's functions.

In the preferred embodiment three radial grippers 24 are provided, i.e.the two side grippers plus the floor gripper. However, should conditionsrequire it, a fourth gripper may be added to engage the roof inconjunction with the side and floor units. There are removable parts inthe gripper shoes 24 which allow the grippers to `straddle` the ringgirders if any increase or decrease in ring density is required.

In addition the apron 16 and hood 17 have alternative bolting positionsso that tunnels of varying diameters within the limits of plus or minus0.25 meters from the norm may be worked.

An advantage of the circular mining machine as hereinbefore described isthat it allows erection of the tunnel support structure over the machinerather than behind it, thus reducing the `prop-free front distance`,i.e. the distance between the cut face and the last permanent tunnelsupport. Further in the event of convergence, the only part of themachine that can become trapped is the hood 17, and another advantage,due to the feature of the boom carriage being moveable independently ofthe machine, is that in the event of sudden convergence trapping themachine against further forward movement, the cutter can be advanced tocut a chamber and the mineral cut thereby can then be removed by hand bypersonnel gaining access to the mineral through the cage and apron/hood.

A further advantage of the circular heading machine as hereinbeforedescribed is its economic rate of advance, cutting 1 meter in each cyclein two cuts of 0.5 meter, while simultaneously allowing support erectionoperations to be carried out in safety.

I claim:
 1. A circular heading machine comprising: an elongate machinebody, means to advance said body in stepwise fashion, a carriage mountedon top of the machine body and slidably moveable thereon longitudinallyand independently of the stepwise movement of the machine body, aforwardly directed cutter boom mounted on the sliding carriage andmanually controlled from an operative position on the sliding carriage,a cage structure surrounding the sliding carriage, and means forerecting tunnel support structures over the machine body, the erectingmeans being provided externally of the cage structure whereby the cutterboom operative can operate the cutter boom during erection of the tunnelsupport structures so that erection of the tunnel support structures andoperation of the cutter can take place simultaneously as the machineadvances in stepwise fashion.
 2. A machine according to claim 1, whereina centering structure is mounted on the rear end of the machine bodytransversly moveable relative thereto and comprises a pair of laterallyextendable members for engagement with the tunnel wall and a dependingmember to engage the tunnel floor, said lateral members having anequalizing displacement so that the depending member is positionedcentrally relative to the tunnel before it is lowered to engage thefloor and in which position it provides a datum point for accuratelydirectional-positioning of the machine.
 3. A machine according to claim1 or 2 wherein the means to advance the machine body comprises incombination a radial gripper means mounted on and longitudinallymoveable relative to the machine body and thrust means connected betweenthe gripper means and the machine body whereby when the radial grippermeans is extended to engage a tunnel wall, the thrust means can move themachine body relative thereto, said gripper means when retracted beingmoveable longitudinally of the machine body.
 4. A machine according toclaim 1 wherein the means for erecting circular tunnel supportstructures comprises a transversely disposed circular framework mountinga chain which is driven around the framework and on which segments ofring girders are mounted and attached to each other in succession, andmeans for expanding the circular chain to enable location of the finalsegment.
 5. A machine according to claim 4 wherein a carrier is mountedon a longitudinal structure which overlies the machine body to deliversegments of ring girders to the erection means.
 6. A machine accordingto claim 5 wherein the longitudinal structure is adjustablelongitudinally and vertically relative to the machine body.
 7. A machineaccording to claim 1, wherein means is provided to limit the peripheralmovement of the cutter boom to form arcuate profile.